Abstract:

Over the last two decades, the organic coatings industry
has undergone rapid technological and structural
changes. These changes have been induced by legislative
actions such as restrictions pertaining to hazardous
chemicals, toxic effluents, and volatile organic
compounds. The consequence of these changes has been
the displacement of almost all commercially-important,
well-established coatings (largely high-solvent
coatings) by newer systems, the formulation and
application of which are based on different chemistries
and technologies. Unlike the displaced coatings,
however, the new coatings do not have performance
histories and the only accepted method for generating
performance data is through an extensive outdoor
exposure program. Since outdoor exposure results
typically take five years to obtain, a desperate need
exists for a methodology which is capable of generating
timely, accurate, and reliable service life estimates of
a coating system. This report reviews the attributes of
the service life prediction problem which are common to
all materials, components, and systems in an effort to
establish a set of criteria for assessing the adequacy
of existing or proposed service life prediction
methodology for coating systems. The current durability
methodology and the reliability-based methodology are
then evaluated against these criteria.

The National Institute of Standards and Technology (NIST) is an agency of the U.S. Commerce Department.